Portal imaging to assess set-up errors, tumor motion and tumor shrinkage during conformal radiotherapy of non-small cell lung cancer
Portal imaging to assess set-up errors, tumor motion and tumor shrinkage during conformal radiotherapy of non-small cell lung cancer
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DOI：
10.1016/s0167-8140(02)00287-6
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发表时间：
2003-01-01
影响因子：
5.7
通讯作者：
Lebesque, JV
中科院分区：
文献类型：
--
作者：
Erridge, SC;Seppenwoolde, Y;Lebesque, JV
目的：研究非小细胞肺癌 3D 适形放射治疗期间的患者摆位、肿瘤移动和收缩。材料和方法：在 97 名患者中，采集电子射野图像 (EPI)，并使用基于收缩作用水平的离线校正方案对摆位进行校正。对于 25 名选定的患者，在整个 6-7 周的治疗过程中评估正交 EPI（在呼吸周期中的随机点采集），以使用叠加和描绘技术确定每张图像中的肿瘤位置。计算每个方向的移动范围。将数字重建放射线照片 (DRR) 中肿瘤的位置与 EPI 中病变的平均位置进行比较。此外，还评估了肿瘤收缩情况。结果：校正后的平均总体设置误差在 x（左右）、y（头尾）和 z（前后）方向上分别为 0、0.6 和 0.2 rum。校正后，x、y、z 方向的系统误差标准差（SD）分别为 1.4、1.5 和 1.3 mm，随机误差 SD 分别为 2.9、3.1 和 2.0 mm。在不进行校正的情况下，41% 的患者的设置误差超过 5 毫米矢量长度，但采用设置校正方案后，该百分比已降至 1%。肿瘤在 x、y 和 z 方向上的平均运动幅度分别为 7.3 (SD 2.7)、12.5 (SD 7.3) 和 9.4 mm (SD 5.2)。肿瘤运动在 y 方向上最大，尤其是下叶肿瘤。 40% 的患者在治疗期间至少在一项投影中肿瘤的投影面积缩小了 20% 以上。在 16 名患者中，可以在 DRR 中定义肿瘤中心的位置。 DRR 中的肿瘤位置与射野图像中的平均位置之间存在 6 mm 矢量长度的平均差异。结论：校正方案的应用导致设置精度显着提高。观察到的肿瘤运动存在很大差异，下叶病变的运动较多。观察到肿瘤缩小。计划 CT 扫描上的肿瘤位置并不总是与治疗期间测量的平均位置一致。 (C) 2002 Elsevier Science Ireland Ltd. 保留所有权利。
Purpose: To investigate patient set-up, tumor movement and shrinkage during 3D conformal radiotherapy for non-small cell lung cancer.Materials and methods: In 97 patients, electronic portal images (EPIs) were acquired and corrected for set-up using an off-line correction protocol based on a shrinking action level. For 25 selected patients, the orthogonal EPIs (taken at random points in the breathing cycle) throughout the 6-7 week course of treatment were assessed to establish the tumor position in each image using both an overlay and a delineation technique. The range of movement in each direction was calculated. The position of the tumor in the digitally reconstructed radiograph (DRR) was compared to the average position of the lesion in the EPIs. In addition, tumor shrinkage was assessed.Results: The mean overall set-up errors after correction were 0, 0.6 and 0.2 rum in the x (left-right), y (cranial-caudal) and z (anterior-posterior) directions, respectively. After correction, the standard deviations (SDs) of systematic errors were 1.4, 1.5 and 1.3 mm and the SDs of random errors were 2.9, 3.1 and 2.0 mm in the x-, y- and z-directions, respectively. Without correction, 41% of patients had a set-up error of more than 5 mm vector length, but with the set-up correction protocol this percentage was reduced to 1%. The mean amplitude of tumor motion was 7.3 (SD 2.7), 12.5 (SD 7.3) and 9.4 mm (SD 5.2) in the x-, y- and z-directions, respectively. Tumor motion was greatest in the y-direction and in particular for lower lobe tumors. In 40% of the patients, the projected area of the tumor regressed by more than 20% during treatment in at least one projection. In 16 patients it was possible to define the position of the center of the tumor in the DRR. There was a mean difference of 6 mm vector length between the tumor position in the DRR and the average position in the portal images.Conclusions: The application of the correction protocol resulted in a significant improvement in the set-up accuracy. There was wide variation in the observed tumor motion with more movement of lower lobe lesions. Tumor shrinkage was observed. The position of the tumor on the planning CT scan did not always coincide with the average position as measured during treatment. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.